5197 on a Worcester Bosch Bosch Compress 5800i Hybrid Heat Pump: Hybrid circulation pump fault (PH0)
Short answer
On a Worcester Bosch heat pump, 5197 means: Hybrid circulation pump fault (PH0). The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Hybrid circulation pump fault (PH0).
Part involved: hybrid circulation pump PH0.
When it shows: Hybrid circulation pump fault (PH0).
Likely causes:
- Voltage too high/low; electronics temperature too high; blocked impeller; pump flowing backwards (generator mode).
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Fault — clears by itself when the condition goes |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: Clears when cause removed.
Manual reset: Manual 12.1: fault indications can be reset on the control unit in the diagnostic menu with Reset.
What you can check
- Read and note the full code (and sub-code) shown on the controller and pass it to your installer.
- If the hybrid system stops using the heat pump, the gas boiler may still provide heat - do not attempt repairs yourself.
What the engineer will check
- Check electrical connection/output voltage, pump ambient temperature, dismantle and check impeller, check hydraulic connection, replace pump if necessary.
Who to ask for: heat pump installer / heating engineer.
Certification: None specific for hydraulic checks; MCS-certified installer recommended for system changes.
What you might notice
Sources
- Installation/operating instructions Hybrid-Set CSH5800iAW O ↗ · 6721875003 (2024/08) · page 40 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026